Submitted to: Peanut Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/27/2008
Publication Date: 4/29/2009
Citation: Jordan, D., Nuti, R.C., Beam, J., Lancaster, S., Lanier, J., Johnson, D. 2009. Influence of Application Variables on Peanut (Arachis hypogaea L.) Response to Prohexadione Calcium . Peanut Science. pages 96-103. Interpretive Summary: In good growing conditions peanut vines can grow to the point where rows are no longer visible. Prohexadione calcium, a plant growth regulator, helps to reduce the length of peanut vines and improves row visibility to make digging peanuts for harvest easier. In some experiments, prohexadione calcium has improved peanut yield, but this not consistent. Although prohexadione calcium works to maintain row visibility, it is expensive, so research was done with several application variables to determine if prohexadione calcium is effective when applied in more affordable techniques. Applying this product in a band or with spray nozzle configurations that reduced total product applied would make it’s use more affordable. Also, if the product could be tank mixed with other necessary products, application costs would be reduced. It is unknown how late season applications of prohexadione affect peanut. Field experiments were conducted with peanut between 2000 and 2006 in multiple locations in North Carolina and Georgia. Applying prohexadione calcium to outer branches of peanut was more effective at increasing row visibility compared with banded applications over peanut main stems or broadcast applications over the entire peanut canopy. Also, better row visibility was possible when prohexadione calcium was applied using spray nozzle configurations that applied the highest rate over lateral branches compared with broadcast applications or putting a higher rate on peanut main stems. Delaying application of prohexadione calcium by 1 week compared to the recommended timing reduced row visibility with all rates tested. Late season applications (within 2 to 3 wks prior to digging) of prohexadione calcium resulted in minor increases in row visibility but did not affect pod yield. Efficacy of prohexadione calcium was not affected when tank mixed with pyraclostrobin or 2,4-DB.
Technical Abstract: Excessive vegetative growth of peanut reduces row visibility during the digging and inversion process. Prohexadione calcium retards vegetative growth, improves row visibility, and in some instances reduces pod shed and increases pod yield compared with non-treated peanut. However, prohexadione calcium is relatively expensive, especially given that yield is not always increased when prohexadione calcium is applied. Additionally, efficacy of late-season applications of prohexadione calcium has not been fully evaluated in peanut. Applying prohexadione calcium to the lateral branches only increased row visibility compared with banded applications over main stems or broadcast applications over the entire peanut canopy. Similarly, greater row visibility was noted when prohexadione calcium was applied using different spray nozzle configurations when the highest rate was delivered over lateral branches compared with broadcast applications of a uniform rate across all spray nozzles or when the highest rate was delivered to main stems. Delaying the first of two sequential applications of prohexadione calcium 1 wk after 50% row closure resulted in poorer row visibility regardless of application rate when compared with sequential applications initiated at 50% row closure. Applying prohexadione calcium within 2 to 3 wks prior to digging and vine inversion resulted in minor increases in row visibility but did not affect pod yield. Efficacy of prohexadione calcium was not affected by pyraclostrobin or 2,4-DB.